Inside the article is a section "How to get started using Backblaze B2 in Terraform" with a link [1] to the getting started guide which should have everything you need.
I can see why they put it on a separate page to not clutter up the article.
I was less interested in the code sample as a "how-to" and more for skimmability – rather than reading a bunch of words I just wanted to see what it would look like.